Trigger mechanism for automatic firearms



Oct. 3, 1950 E. HEPPERLE 2,524,258

' TRIGGER MECHANISM FOR AUTOMATIC FIREARMS Filed Feb. 25,1946

mus/v70) 20 '3 240 ERW/A/ fi EPPERLE MTDRNEKE i atenteci ct.

Erwin Hepprle, Zurich, Switzerland; assignor to Verwaltungsgesellschaft der Werkzeugmaschin- V enfabrik Oerlikon, Z

land

Application February 26, 194.6,fSeri'al No. 650,174

urich-OerIikon, Switzer- In Switzerland February 28, 1945* Automatic fire arms include, in the; trigger mechanism devices intended to catch the breech block after the release of the last shot. It. is essential in such devices that the contact between catch hook and catch nose should be established SiCIaims. .l 7

over the whole face so as not to damage the edges and impair in a short time the correct working of the catch device.

Fig. 1 a schematical representation, ire-sec v tion; of an automatic fire arm; 7 j Fig.2 is a section throughthe trigger mechanism,v the breech block being in locked position;

Fig. 3 is a section through the triggermechanism as the sear actuating lever is starting its" rotating motion;

In a known device of this kind the catch. hook is pressed by a spring out of the range of the catch nose; by releasing the firing or sear actuating lever a pawl indirectly causes the projection of the catching face of the sear or catch hook into the path of the catch nose of the breech block whereby the catching face of the sear is brought within the range of a nose provided on the breech block.

Practice has shown, however, that this known device, as a result of vibrations in the trigger mechanism which cause a back spring action of the catch devices, does not guarantee with absolute reliability a full-face contact of catch hook and catch nose, thus making it impossible to avoid damage to the faces and more particularly to the edges. Moreover, the set-up of this known design is complicated, due to the fact that vthe pawl actuated by the release of the firing lever controls only indirectly-i. e. over various .other membersthe projecting of the catching ,face of the sear or catch hook into the path of the catch nose of the breech block.

The present invention relates to a trigger mechanism reliably securing full-face contact of .catch hook and catch nose, and of extremely simple design compared with known types.

In the trigger mechanism for automatic fire arms according to the present invention a pawl is articulated on the locking lever or sear, which pawl can be actuated during the forward travel of the breech block both from the firing or sear :actuating lever and from a control face provided -on the breech block, the pawl, having surfaces .which in the end positions of its free travel, come into contact with corresponding surfaces on the .sear, so that the latter must compulsorily carry out the movements of the pawl as directed by the sear actuating lever or the catch nose on the breech block. The pawl can suitably be of such design that, in the locked position of the breech, it lies on the latter, thus securing the looking lever or sear and rendering impossible the release of the breech through shocks or the like. The accompanying drawing shows in Figs. 1-7 .a constructional example of realisation ofthe present invention.

Fig.34 is asection through the trigger mechanism, with searactuating lever completely pulled and*breech-.block released;

Fig. 5 is a section through the trigger-mechanism, with released sear actuating lever,-..a!? the :-moment whenthe breech block locking motit'm is spring 4., Thebreech block 3 is fitted with a nose 5 3a which engages with the locking face, Bpf the locking lever or sear 6. The sear 6 is pivotally .mountedon a pin 1 inthe trigger casing and is a responsive to the action of a spring 8 which has a the constant tendency to force it into theposition 'sh own in Fig. 4, i. e. out of the way of the catch nose 3a. On the side opposite to the locking face-5 the sear 6 is of fork shape and-carries the pawl l0 movably seated by means of. the pin 9 to which it is secured. In a hole of the sear 6 is located a spring 'Il pressing against .the' pawl I0 -and attempting to force it into the position shown in Figs. 2 and 5. The pawl. Ii! isfitt'edin the sear S in such a manner that after ashort free travel either its face lflacomes into contact with the corresponding-face-fia of the sear, or its face lb with the face 61) of said sear.

The sear actuating lever I2 is mounted b means of .pin [3 in the trigger casing andfis actuated inknownmanner, not represented'ihere. diprojection Ila of the sear actuatinglev'fer l2 1 is responsive to the action of a spring [4' located in the trigger casing, which on releasefof the trigger moves the leverback into rest position.

The lever l2 acts by means of a finger Men thepawl Ill.

The pin 9 by means of which the pawl lfl is seated in the sear 6 has on one side an enlarged head 16. This headlfi'is provided witha slot 11 into which catches the pin I8 of the safety'lever The safety lever is is spring-loaded by a [9. spring 20 which forces thepin l8 into'the slot 11 in the head It of the pin 9. By lifting the pin -wise round the pin 9.

- begins. position, as shown in Fig. 4, continuous fire is I8 of safety lever [9 against the pressure of the spring 20, the lever l9 can be swung round the pin I 3 on which it is pivotally mounted.

The breech block 3 is furthermore provided with a cam face 2! which is adapted to engage the pawl" ID whenthe latter isinthe position shown in Fig. 5.

The trigger mechanism described above per-- ates as follows:

Before actuating the vsear'actuating lever [2 the safety lever H) which keeps locked the pivot pin 9 of the pawl l6the latter, in thelockedposition of the breech block isecuringt. at ,the.

same time the sear 6-must first be shifted. --This is done by pulling the pin l8 out of the slot I! of on further actuation of the pawl in either direc tion the sear must follow the movements of the pawl about the axis of the sear, a breech block having a cam surface adapted to engage the pawl,

when it isI atone of it. s-,limit s of, free rotational .movement, alever arranged also lt -actuate said pawl, actuation of the pawl by said lever causing the sear to rotate and release the breech block, and actuation of the pawl by the cam surface of the breech block causing the sear to return into locking position.

2. Trigger.m echanism according to claim 1 ineluding aspring disposed on the sear and acting to'urge the-pawl into the path of the cam surface the head H6 in the pin Q af ter which the safety lever I9 can be swung around the pinklli'l'he j pawl Ill is now released, by clockwise rotation of sear actuating lever I2, whereby the latters finger I5 will cause the pawl H] to rotate counterclock- As aresult /the spring I I is first compressed until the pawl l0, with its face 40b, comes into contact with the corresponding facetb of the sear 6 (Fig, 3). on-f-urtherrotation the sear actuating lever the sear 6 by way ofthepawl i0 whichis-now in contact with the sear at 5b.-- 'As a result, the

locking face 5 of the scarf; moves out of-the catch nose 3a of the breech-block 3.- This position is shown in Fig. 4. --The breech-block now moves forward through the action of spring 4 and firing If new the lever 12 is kept in its rotated kept up. It will be understood that the construction of the breech block is such that the nosei3a does not strike the pawl I0. As soon; however, as the lever i2 is released, the-pawl--l0, under the action of the spring II, takes up anerect posi- 7 tion, so that its face lila comes into contact with the face 6a of the sear 6.- In this position, the

pawl protrudes into the path ofthe guiding face 1 2[ since the sear is still held in its rotated position by the spring 8.

After its rear reversal, that is, when moving forwardly toward the gun breech,

' the breech block, with its guiding face 2l, actuates the pawl I 0, thus pressing upwardly the pawl-carrying end of the sear 6 and bringing the locking face 5 within range of" the catch nose 3a on the breech block 3.

The present inventionprovides with simple means a trigger mechanism reliably securing fullface engagement of the locking face 5 of the sear with the catch nose 3a of the breech block 3, and affording in addition absolute security against the accidental release of the breech block through vibrations.

I claim:

1. Trigger mechanism for automatic firearms, comprising a pivoted sear movable into position to lock the breech block, a pawl pivotally mounted on said sear so as to have limited free rotational movement in opposite directions relative to the sear, said pawl having surfaces which in the end position of its free movement come into contact with corresponding surfaces on the sear, whereby I2 also rotates of the breech block.

3. Trigger mechanism according to claim 1,

whereinthe breech block is provided with a catch nose into whose path the sear is moved when the pawl'is actuated by the cam surface of the breech block and has beeniacaused to rest on top of the breech block, whereby the sear isllockediagainst the cathtnose ofthebreechblock, and aspring actingon-saidsear, saidispring retaining thesear in its rotated. position t after theusear. actuating lever hasbeen-released,...until the sear is. returned into locking-position;by-theipawl.

4. Trigger mechanismcforautomatic firearms, comprising a pivoted searsmovableinterposition to. engage the-breech. blockt totlockuthe same against-forward movement, a spring normally urging theisear into inactive .condition, a sear acwhereupon saidlpawllandesear a e. rotated as a unit about-the pivotal ,axisofthe sear, to :bring the latter inter-locking engagement. with. the

breech block.

5. Trigger. mechanism .according to .claim 4 wherein thepawl isso dimensioned that it, rests on the breech .blockin -.the.. locked. po,sition of the latter and .thus servesto holdrthersear in.1ocking position against theactionofthe first mentioned spring.

,rERWIN. HEEPERLE.

aErrBsNcEs ,c r-E 'The following references are of record in the file of this patent:

UNlTED STATESPATENTS 

